1. Field of the Invention
The present invention relates to a 3D image projection optical system for converting a 2D projector image into a 3D image on a screen.
2. Description of the Related Art
Currently, 3D images are provided in the market in DVDs and broadcasting for a sports game such as a soccer, etc.
During broadcasting a 3D image, the 3D image is transmitted as one image by reducing a left-eye image 101 and a right eye-image 102 in half to transmit to a left and right side or a top and bottom side in one frame 103.
That is, as in the frame 103 shown in FIG. 1, a picture having a ratio of 16:9, i.e., a lateral size to a vertical size ratio of the left-eye image 101 and the right-eye image 102, is reduced to 8:9 to form one picture 103 having a picture ratio of 16:9 which is input into one channel or one input device.
Here, when the 3D image is projected to a general projector as shown in FIG. 1, the left-eye image 101 and the right-eye image 102 are used to form a screen image 104, which is only viewable as the individual images which are reduced to ½ aspect ratio and viewed on the leftward and rightward or top and bottom sides of the picture, and cannot be viewed as 3D image.
Although there is technology that proposes to separate the left-eye image 101 and the right-eye image 102; according to the technology, even though the left-eye image and the right-eye image are projected on a screen, the images are viewed as vertically elongated images, as shown in the screen image 104 of FIG. 1, which is not practical for viewing. Especially, with respect to a picture size, there is no technology that is able to simultaneously combine the technology that magnifies the leftward and rightward images that leaves the image in its original vertical size with a technology that separates the images.
In order to solve the aforementioned drawbacks, according to a prior art, an electronic division device 105 in which a separate image division and magnification circuit board is embedded is provided in a 3D image projector to divide the left-eye image 101 and the right-eye image 102 placed in one frame 103. After that, the reduced leftward and rightward pictures are magnified to their original sizes and the left-eye image 101 and the right-eye image 102 are projected at a time interval on a screen, as shown in FIG. 1 as 107a and 107b. These images are then viewed through the shutter-type eyeglass for 3D imaging 109 in which the left and right sides are opened and closed in a synchronizing manner.
However, a shutter unit, a synchronizing signal, and a receiving unit, etc., have to be provided on the shutter-type eyeglass 109, and thus the eyeglass itself is heavy and inconvenient and is also expensive. Thus, the shutter-type eyeglass has not been used for a large screen for multiple viewers, which is usually installed in a theater, sports café or assembly hall.
Further, since the time signal for exchanging the left-eye image and the right-eye image have to be received from the screen to the 3D image eyeglass 109 to simultaneously drive the shutters of the 3D image eyeglass, the signal is weakened to a viewer placed at a remote distance from the screen and thus the viewer can not clearly see the 3D image.
Alternatively, a polarization wheel has been provided in front of the 3D image projector through which the left-eye image 101 and the right eye image 102 are projected at a time interval on a screen to be viewed through a 3D image eyeglass 108. However, the polarization wheel configuration has a complicated design and the brightness of the image is reduced by ½ and further is reduced to ½ through the polarization wheel which greatly decreases the picture quality.
Further, the left-eye image 101 and the right-eye image 102 can be respectively projected at different angles and overlapped on a screen 106 by generally using two projectors. The left-eye image 101 and the right-eye image 102 are then viewable by a left eye and a right eye, respectively, as a 3D image by using a polarization eyeglass 108 having the same polarization angle as the projection lens.
In summary, there has been no technology in the prior art except for viewing a 3D image other than a 3D image shutter eyeglass 109 system using one projector and a polarization eyeglass system that uses two projectors or two projection engines.
In these cases, two projectors or a projector having two optical engines are used in order to use the polarization eyeglass. Additionally, a complicated polarization wheel can be used in order to use the polarization eyeglass with one projector.
Accordingly, there is a need for a technology that divides a 3D image combined in one frame 103 and at the same time magnifies and polarizes the image to be clearly viewed by using a general projector through a polarization eyeglass for 3D image viewing.